Combined air fan and clutch for engine cooling



June 2, 1953 I. 1. SIKORSKY 2,640,469

COMBINED AIR FAN AND CLUTCH FOR ENGINE COOLING Original Filed May 9 19453 Sheets-Sheet 1 m9 IGOR u. SIKORSKY INVENTOR BY M I3; 0744 ATTORNEYJune 2, 1953 ll. SIKORSKY 2,640,469

COMBINED AIR FAN AND CLUTCH FOR ENGINE COOLING Original Filed May 9,1945 3 Sheets-Sheet 2 IGOR l. SIKORS'KY INVENTOR BY 2. may

A'ITORNEY June 2, 1953 l. 1. SIKORSKY 2,540,459

COMBINED AIR FAN AND CLUTCH FOR ENGINE COOLING- Original Filed May 9,1945 3 Sheets-Sheet 3 IGOR I. SIKORSKY INVENTOR ATTORNEY Patented June2, 1953 CQMBINED AIR FAN AND CLUTCH FOB. ENGINE COOLING Igor I.Sikorsky, Bridgeport, Oonn., assignor to United Aircraft Corporation,East Hartford, Conn, a corporation of Delaware Original application May9, 1945, Serial No. now Patent No. 2,517,509, dated August 1;, 1950.Divided and this application May 20, 1949, Serial No. 94,441

This application is a division of 'my copending application Serial No.592,862, filed May 9, 1945, which issued on August 1, 1950, as PatentNo. 2,517,509.

The present invention relates to improvements in aircraft, and moreparticularly to an improved aircraft of the direct lift type such asthose shown in my prior patents, Nos. 2,318,259 and. 2,318.260, andordinarily referred to as helicopters.

It is an object of this invention to provide improved power transmissionand engine cooling means for aircraft of this type.

A further object of the invention is to provide an improved combinedengine power output clutch and engine cooling fan structure particularlyadapted for use in aircraft.

' The foregoing and other objects, including the details of constructionand arrangement of parts of the instant invention, will be eitherobvious or pointed out in the following specification and claims takenin view of the accompanying drawings in which:

' Fig. l is a side elevation of a helicopter embodying my invention;

' Fig. 2 is a side view of the front portion of the helicopter withparts broken away and parts in section to show the general constructionandarrangement of the helicopter control and drive mechanisms;

Fig. 3 is a perspective view of the reduction gear mechanism, thecombined engine cooling fan and engine power clutch mechanism and thebrake mechanism, the engine being omitted to facilitate illustration;and

' Fig. 4 is a side view partly in section of the em gine and my novelcooling fan and clutch mechanism for the engine.

' As shown in Fig. 1, the helicopter embodying. this invention includesan elongated body it having a forward pilots compartment [2 in which theseats and controls are contained, and an empennage section [4 upon whicha torque compensating tail rotor 16 is mounted for rotation about agenerally horizontal axis it. The main rotor for the helicopter isdriven by an up-'. right hollow drive shaft 20 which extends ulfiwardlythrough a nylon 22 and drives a plurality of main rotor blades 24 whichare p'lvotally mounted on a rotor head 25 for movement about flappingand drag hinges.

' The usual controls for the rotor blades are provided including thecollective control lever 28 (Fig. 2) and azimuthal control stick, or joystick; 30 located in the pilots compartment and conneoted through theusual control levers to a 13 Claims.v (Cl. 123-2) 2 swash platemechanism 32 comprising a part of the rotor head.

An engine 34 of the radial air cooled type is mounted in the body illjust aft of a fire wall 36 which separates the engine compartment fromthe pilot compartment. ranged'cylinders 88 of the engine which are provided with the usual cooling baffles 40 are enclosed in a cowling 42(Fig. 2) having an outwardly flared flange 44 facing aft in the fuselageand an air exit opening 46 facing forward.

The engine crankshaft 48 (Fig. 4) which ex tends aft in the fuselagecarries a. combined clutch and fan mechanism generally indicated by thenumeral 52, the fan serving to circulate cooling air for the engine andthe clutch serving to control the power output of the engine asdeveloped at the engine crankshaft 48. This mesh anism includes anassembly 53 of fan and clutch elements fixed to the crankshaft 4B andcompris ing the driving portion of the clutch and a bellshaped element54 rotatably mounted on the crankshaft and comprising the driven elementof the clutch. The driven element 54 is connected through a freewheeling unit 55, universal joints 53 and 58, and a shaft 59 to the gearre-' duction mechanism 60 (Fig. 2) which may be of any suitable type,and in the instant device provides a gear ratio of 9.336/1 for drivinthe rotor shaft 20. A higher speed portion of the gear reductionmechanism-turns a shaft 62 connected by universal joints 64 to the tailrotor drive shaft 66. An oil sump 1B is formed as a portion of thecasing for the gear mechanism 60 and is equipped with fins for coolingthe oil. An oil tank '12 which has a filling and air vent i4 is mountedupon a platform It carried by adjac nt structural members of thefuselage.

Cooling air for the engine 34 is drawn into the interior of the fuselageI0 through an opening 16 in the forward portion of the pylon. The airtravels downwardly and. around the gear reduo tion mechanism 60 and isdrawn forward through the engine cowling 42 by a fan 86 (Fig. 4) whichcomprises a plurality of blades 82, the shanks of which are rigidlyconnected by means of bolts 84- to the periphery of a plate member 86comprising the main element of the driving-portion 5.2 of the clutch.Theair, after passing through the cowling A52, is directed downwardlyand to the sides by the fire walls 36 and passes out of the fuselagethrough suitable holes, not shown.

The smooth flow of cooling air through cowling 42 and the cooling finsof engine 34 is enhanced by an annular bailie 81 which forms anextension The peripherally ar of late member 86 and terminates at itsouter periphery in an aft directed, inwardly flared cowling ring 88.Ring 88 is conjunction with the outwardly flared flange 44 of baflie 42defines an annular air inlet for the cooling airstream in which theblades 82 operate. Baflie 81 is secured at its inner periphery to theperiphery of plate member 86 by the same bolts 84 by which the shanks ofblades 82 are secured thereto. It will be evident from Fig. 4 that theshanks of blades 82, which lie adjacent and aft of bafile 81, extendthrough apertures 89 in the latter and are secured to the baffle at thebase of ring 88 by a series of bolts 98.

Plate member 86 is rigidly secured to the engine shaft 48 by opposedannular wedge members fore and aft thereof and carries an annularpressure plate member 84 which surrounds the hub of plate member 86 andis constantly urged to the left as viewed in Fig. 4 by a plurality ofcompression springs 96, each of which bears at one end against plate 94and at its opposite end against cup-shaped washers 88 secured by nuts 89on one end of a bolt I88 carried by plate member 86. A clutch plate I82is mounted between the driving clutch member and pressure plate 94 andcooperates with the adjacent face I84 of plate member 86. Clutch plateI82 comprises a flat annulus having its outer periphery toothed, orsplined, to mesh with corresponding internal teeth, or splines, formedin the periphery of bell-shaped driven clutch member 54 which isrotatably mounted on the aft end of engine crankshaft 48 by means ofspaced ball bearings I86. Clutch member 54 is connected to free wheelingunit 55 by a series of annularly disposed bolts I87.

Control of the clutch is obtained by a manual control lever I88 (Fig. 3)located in the pilot compartment and pivoted to a fixed part of thecraft at I89. Rod II8 pivotally connected to lever I88 at III is pivotedat I I2 (Fig. 4) to the lower end of a yoke lever II 4 pivoted at II6 ona lug II8 on the engine crankcase. The upper free ends of yoke lever II4move a collar I28 fore and aft along the axis of engine shaft 48, thecollar I28 being axially slidable along a coaxial tubular member I22forming an integral part of the crankcase of the engine. Collar I28 issecured to one race I24 of a ball bearing and holds the samenonrotatable. of the bearing is free to turn, and engages the free endsof a plurality of levers I28 pivotally supported at their opposite endsat I29 on lugs I38 on plate member 86. Levers I28 engage a series ofthrust pins I32 which are slidably extended through plate member 86,pass through the central opening in annulus I82 and are adjustably screwthreaded into the pressure plate member 94.

An electrical starter I34 (Fig. 3) is connected by wires to a springloaded switch I86 having switch operating lever I38 disposed in the pathof a lug I48 which is attached to lever I88. A conventional manuallyoperated starter switch, not shown, is in series with the spring loadedswitch I36. Only when the lever I88 is in the full forward position sothat lever I38 is held depressed by lug I48, can the starter circuit beclosed by the conventional manual switch. When thelever I88 is fullyforward, the clutch is in the disengaged position.

Lever I88 is also connected by a cable I44, which passes over a seriesof pulleys I46, I48 and I58, with the rotor brake operating lever I52,and is constantly biased into the clutch-engaging or Another race I26 4brake releasing position by tension spring I54 acting on lever I52.

In operation the pilot squeezes the top of lever I88, which has pivotedon it a handle I42, and thereby withdraws lug I43 from engagement with atooth quadrant (not shown). The lever I88 is moved in the forwarddirection until the lug I48 engages the switch operating lever I38 atwhich time the pilot can start the engine by operating the conventionalstarter switch. In this position the rotor brake will be engaged. Aftera sufficient period of warm up of the engine, the pilot moves the clutchcontrol lever I88 aft to a mid position of its travel. At this point therotor brake is released, while the clutch is still not engaged. Bymoving lever I88 further aft, the clutch is then gradually engaged andtransmits the engine torque to start the rotor turning. After asuflicient period of warm-up of the engine, the pilot moves the clutchcontrol lever I88 aft to first release the brake and then to graduallyengage the clutch, utilizing his other handto control the collectivepitch control lever 28 and the engine throttle.

It will be noted from Fig. 4 that as the lever I88 is moved aft the yokelever II4 moves counterclockwise about its pivot I I8 which causes thecollar I28 to be moved forward. This results in the forward movement ofthe free ends;

of levers I28 which control the thrust pins I32 and allow the latter andpressure plate 94 to move forward under the bias of clutch springs 86.As the pressure plate 84 moves forward (to the left in Fig. 4), it movesthe clutchplate- I82 to the left into engagement with the flat face I84of the driving clutch member 88, thus connecting the latter with thedriven clutch member 54 and establishing a driving connection throughthe clutch mechanism to the gear mechanism 68.

In order to get maximum efficiency, that is maximum torque capacity fora minimum overall weight of structure using either a disc clutch or acentrifugal type clutch, it has been found best to design these clutcheson the basis of as large a diameter as possible. cooling fan directly onthe driving portion of the engine clutch, the fan is always rotated atengine speed, regardless of whether the rotor is turning, and providesin a helicopter the most advantageous location for mounting the coolingfan. Conversely, the cooling fan is best mounted nearthe engine and bymy improved construction the clutch can be advantageously mounted on theengine shaft. By this arrangement such power consuming devices asaccessory drives are elimi-.

1. In a helicopter, an engine having radial air cooled cylinders, arotor driven by said engine, cowling means surrounding said enginecylinders having an air inlet, a clutch disposed in said .cowling inletcomprising a driving member con- By mounting the 5, nected to saidengine and a driven member connected to said rotor for controlling thepower output of said engine, and cooling fan blades carried by theperiphery of said driving member.

2. In a helicopter including an engine having a crankshaft and radialair cooled cylinders, air passage means for directing a coolingairstream over said cylinders, a clutch having driving and drivenmembers, said driving member being connected to said crankshaft and saiddriven member being rotatably mounted on said crankshaft, an innercowling ring carried by said driving clutch member in spaced relation tothe walls of said passage means, and a fan carried by said drivingclutch member having blades rotatable in the annular space between thewalls of said passage means and said inner cowling.

3, In a helicopter, an enginehaving radial air cooled cylinders, cowlingmeans surrounding said engine cylinders having an air inlet, means forcontrolling the power output of said engine in cluding a clutch disposedin said cowling inlet having driving and driven members, said drivingmember forming a central barrier in said air inlet, and cooling fanblades carried by the periphery of said driving member in the annularspace between the latter and said cowling.

4. In a helicopter, an engine having air cooled cylinders, cowling meanssurrounding said engine cylinders having an air inlet, means forcontrolling the power output of said engine including, a clutch disposedin said cowling inlet having driving and driven members, said drivingmember forming a central barrier in said air inlet, cooling fan bladescarried by the periphery of said driving member in the annular spacebetween the latter and said cowling, and inner cowling means carried bysaid driving clutch member at the base of said fan blades.

5. In a helicopter, an engine, said engine having a crankshaft and aircooled cylinders extending radially from said crankshaft, cowling meanssurrounding said engine cylinders and. having an air inlet for directinga cooling airstream over said cylinders, means for controlling the poweroutput of said engine including a clutch comprising a driving clutchmember disposed in said inlet and fixed to said crankshaf and a drivenclutch member rotatable relative to said crankshaft, said driving clutchmember having its outer periphery spaced from said cowling, and acooling fan carried by said driving member including fan blades extendedradially into the space between the periphery of said driving member andsaid cowling.

6. In a helicopter, an engine, said engine having a crankshaft and aircooled cylinders extending radially from said crankshaft, fixed cowlingmeans surrounding said engine cylinders for directing a coolingairstream over said cylinders, means for controlling the power output ofsaid engine including a clutch disposed in said cowling means comprisinga driving clutch member fixed to said crankshaft and a driven clutchmember rotatable relative thereto, said driving clutch member having itsouter periphery spaced from said cowling means, cooperating rotatablecowling means carried by the periphery of said driving member anddefining with said fixed cowling means an annular air passage fordirecting cooling air to the engine, and a cooling fan including bladesattached to said rotatable cowling means and extended into said annularair passage.

'7. In a helicopter, an engine, said engine hav- 6. ing a crankshaft andair cooled cylinders .extending radially from said crankshaft, cowlingmeans surrounding said engine cylinders and having an air inlet fordirecting a cooling airstream over said cylinders, means for controllinthe power output of said engine including a clutch disposed in saidinlet comprising a driv ing clutch member fixed to said crankshaft and adriven clutch. member rotatable relative thereto, said driving clutchmember having its outer periphery spaced from said cowling means, radialfan blades having their shanks secured to said periphery and havingblade portions located ad- J'acent said cowling means, and rotatingcowling means attached to said driving clutch member and locatedadjacent the shank portions of said blade, said rotating cowling meanscooperating with said stationary cowling means to form an annularcooling air passage in which said blade portions operate.

8; In a helicopter, an engine having radial air cooled cylinders and anaxial crankshaft, means for controlling the power output of said engineincluding a driving clutch member fixed to said crankshaft having anannular clutch face, a pressure plate carried by said driving clutchmember having means constantly biasing it. toward said clutch face, adriven clutch member rotatable relative to said crankshaft having aflange which terminates adjacent said driving clutch member, theperiphery of said flange having an internally splined surface thereon,an annular axially floating clutch plate having an outer splinedperiphery meshing with the splines on said driven clutch member andoverlying the clutch face on said driving clutch member between thelatter and said pressure plate, and means for moving said pressure platemember against the bias of its springs to disengage said clutch.

9. A combined fan and clutch mechanism for a rotary wing aircraft of thetype having an air cooled engine for driving the rotor, said combinedfan and clutch mechanism including a clutch between the engine and therotor for controlling the application of engine power to the rotorhaving driving and driven clutch members, means for directing a streamof cooling air over said engine including a streamlined annularpassageway the outer wall of which is stationary and the inner wall ofwhich is carried by one of said clutch members, and fan blades in saidpassageway carried by the periphery of said driving clutch member.

10. A combined fan and clutch mechanism for a rotary wing aircraft ofthe type having an air cooled engine including a crankshaft and cowlingenclosing the engine forming air passage means for directing a coolingairstream over the engine cylinders, said combined clutch and fanmechanism including a driving clutch member driven by the crankshaft ofthe engine and a driven clutch member rotatable relative thereto, aninner cowling ring carried by said driving clutch member in spacedrelation to the walls of said passage means, and a fan carried by saiddriving clutch member having blades rotatable in the annular spacebetween the walls of said passage means and said inner cowling,

11. In a helicopter, an engine having air cooled cylinders, a rotordriven by said engine, streamlined oowling means having an air inlet andan air outlet discharging air over said cylinders, a clutch disposed insaid cowling inlet comprising a driving member connected to said engineand a driven member connected to said rotor for controlling theapplication of engine power to said rotor, and cooling fan bladescarried by the periphery of said driving member.

12. In a helicopter including an engine having a crankshaft and aircooled cylinders, air passage means for directing a cooling airstreamover said cylinders, a clutch having driving and driven members, saiddriving member being connected to said crankshaft and said driven memberbeing rotatably mounted on said crankshaft, an inner cowling ring havingan exterior airfoil surface carried by said driving clutch member inspaced relation to the Walls of said passage means, and a fan carried bysaid driving clutch member having blades rotatable in the annular spacebetween the walls of said passage means and the airfoil surface of saidinner cowling.

13. A combined an and clutch mechanism for a rotary wing aircraft of thetype having an 20 air cooled engine including a crankshaft and cowlingforming air passage means having an inner airfoil surface for directinga cooling airstream over the engine cylinders, said combined clutch andfan mechanism including a driving clutch member driven by the crankshaftof the engine and a driven clutch member rotatable relative thereto, aninner cowling ring having an exterior airfoil surface carried by saiddriving clutch member in spaced relation to the walls of said passagemeans, and a fan carried by said driving clutch member having bladesrotatable in the streamlined annular space between the 5 walls of saidpassage means and said inner cowling.

IGOR. I. SIKORSKY.

References Cited in the file of this patent 10 UNITED STATES PATENTSNumber Name Date 911,382 Choston Feb. 2, 1909 1,422,426 Farr July 11,1922 15 1,456,699 Kramer May 29, 1923 1,551,055 Rieseler Aug. 25, 19251,837,564 McCaleb Dec. 22, 1931 1,934,399 Bleecher Nov. 7, 19331,934,783 Arterburn Nov. 14, 1933 2,274,743 Rosskopf Mar. 3, 19422,379,015 Lysholm June 26, 1945 2,407,223 Caldwell Sept. 10, 19462,457,692 La Brie Dec. 28, 1948 FOREIGN PATENTS 25 Number Country Date874,323 France Apr. 27, 1942 875,651 France June 29, 1942 315,877 ItalyMar. 10, 1934

